SEM of Mg/Pd

Zero-Valent Bimetals• Zero-valent bimetals have been shown to

reduce chlorinated compounds• Zero-valent substrate provides thermodynamic

driving force:– Mg2+ + 2e- Mg0 Eo = -2.20 V

– Fe2+ + 2e‑ Fe0 Eo = -0.44 V

• Oxidation reaction provides source of molecular hydrogen:

– M0 + ROH H2 + M2+ (R=H, CH3)

• Mechanically alloyed zero-valent metals are combined with known hydrogenation/reduction catalysts:

– Pd and Ni

20 min

Emulsified Zero-Valent Metal (EZVM)

• Combination of emulsified liquid membranes (ELM) and zero-valent bimetal:

– emulsion droplet provides protective reaction barrier

• Emulsion droplet:– organic membrane, water interior,

surfactant, and active metal

• In-situ technology to remediate:– water and soil contamination– wet TATP contamination

Summary and Future Directions

• Bimetals are shown to successfully degrade nitro explosives (TNT and RDX) and TATP

• EZVM and BTS are continued to be explored and optimized to clean-up both dangerous TATP contamination and environmentally hazardous nitro explosives contamination

• Further exploration includes:– reaction pathways – final byproducts

• Field application:– soil and groundwater nitro explosive contamination near

industrial production sites– structures/scrap metal and ordnance due to incomplete

detonation– clean-up of TATP residue in underground labs

Objectives

Degradation of TATP, TNT, and RDX using Mechanically Alloyed Bimetals

Christian A. Clausen, Cherie L. GeigerChristian A. Clausen, Cherie L. Geiger, , Rebecca FidlerRebecca Fidler, , Michael E. Michael E. SigmanSigman

Department of Chemistry, University of Central FloridaDepartment of Chemistry, University of Central Florida

• Optimize the use of zero-valent metals (ZVM), emulsified zero-valent metal (EZVM) systems, and bimetal treatment systems (BTS) to degrade TATP, TNT, and RDX contamination

• Develop an in-situ method for degradation of common explosives TATP

• Triacetone Triperoxide• Prepared from common materials:

– acetone, hydrogen peroxide, and acid catalyst

• Sensitive to shock, friction, and heat • High vapor pressure (7 Pa)• Incidents involving TATP:

– Richard Reid “The Shoe Bomber” used PETN with TATP (2001)– London bombings (2005)– Oklahoma University (2005)

Kinetics Experiments

TNT (2,4,6-Trinitrotoluene)

Nitro Explosives

• Environmentally hazardous:– considered toxic and mutagenic

• Types of contamination: – soil and groundwater – metal scraps and ordnance

CH3

NO2

NO2

O2N

O

O

C

C

H3C CH3

O

O

H3C

H3CO

O

C CH3

CH3

N

N

N

NO2O2N

NO2

RDX (cyclo-1,3,5-trimethylene-2-4-6-trinitramine)

TATP crystal

TATP crystal 1 min 6 min

Micrograph of Emulsion Droplet

TATP crystal absorbed into an emulsion

Bimetal Treatment System (BTS)

• Provides an in situ technique for handling explosive contamination on structures and scrap metal

• Paste consisting of active bimetal, solvent and thickeners

• Can be applied directly to contaminated structures or scrap metal

Application of BTS

TATP

A=Acetone

A=TATP

• Vial studies performed in methanol/water solution

• Pseudo-first order rate law:– rate=-kTATP[TATP]

• Acetone was observed as major byproduct

• Other byproducts being explored:

– CO2, ethane, O2, and methane

• Half-life for TATP degradation = 11.5 min

Kinetic data of TATP degradation with MgPd and acetone byproduct

production

TNT

Kinetic data of TNT degradation with various bimetals/metals

MgPd

FeFeNi

FePd

• Vial studies performed in water

• Pseudo-first order rate law:– rate=-kTNT[TNT]

• Byproducts observed: – 2,4-dinitrotoluene (DNT)– 2-amino-4,6-dinitrotoluene

and 4-amino-2,6-dinitrotoluene (ADNT)

• Half-life data for TNT degradation:Metal Half-Life (min)

Fe NA

Mg/Pd 25

Fe/Pd 3

Fe/Ni 51

RDX

Kinetic data of RDX degradation with various bimetals/metals

• Vial studies performed in water

• Pseudo-first order rate law:

– rate=-kRDX[RDX]

• Common cyclic byproducts are not observed which suggests:

– ring cleavage– production of lower

molecular weight gases

• Half-life data for RDX degradation:

Metal Half-Life (min)

Fe NA

Mg/Pd 92

Fe/Pd 210

Fe/Ni 433

Mg/Pd Fe/Pd

Fe/Ni

Fe

TATP crystal

20 min

Fe

Fe/Pd

Fe/Ni

Mg/Pd

0

0.2

0.4

0.6

0.8

1

1.2

0.00 10.00 20.00 30.00 40.00

Time (min)

C/C

o TATP

Acetone